Many bone conduction hearing aid manufacturers claim: "The products are suitable for various degrees and types of hearing loss." Bone conduction hearing AIDS are mostly suitable for mild to moderate conductive deafness and some mixed deafness.
Experts say that many hearing AIDS claimed online to be dispensed with can become noise sources when worn by patients. Over time, they may even cause the remaining hearing to decline. The promotion of "no need for fitting" and "applicable to multiple degrees..." undoubtedly exaggerates the efficacy and misleads consumers. For people with hearing impairments, if they purchase hearing AIDS that are not suitable for them, it can be said that they are "losing both the wife and the army", not only spending money in vain but also causing further damage to their hearing.
How can we rationally choose hearing AIDS and avoid spending money in vain?
First of all, it is necessary to know: What are the principles of air conduction and bone conduction hearing AIDS?
Under natural conditions, sound travels through our external auditory canal - eardrum - middle ear - inner ear to reach the auditory center. A common air conduction hearing aid converts amplified electrical signals into sound signals and transmits them into the ear canal, simulating the natural state of hearing in the ear. Normal human hearing relies on the "air conduction channel". Bone conduction hearing AIDS, on the other hand, convert amplified electrical signals into mechanical vibrations and transmit these vibrations to the skull closely attached to the vibrator, driving the vibration of the cochlear lymph fluid within the temporal bone to transmit sound.
Why do air conduction hearing AIDS have more advantages than bone conduction hearing AIDS for the majority of people with hearing loss?
The way air conduction hearing AIDS listen to sounds conforms to the innate auditory habits of human beings. Our auditory experiences from childhood to adulthood are all established through "air conduction" (such as chatting with others or listening to music). The sound transmission method of air conduction hearing AIDS is exactly the same as that of normal hearing, and the brain does not need to "adapt" additionally. The sound produced by bone conduction is "the perception brought by the vibration of the skull", which is quite different from the daily auditory experience. After the wearer uses it for the first time, they will feel that the sound "seems to come from their own head" (that is, the "cranial ringing sensation"), and it takes a relatively long time to adapt. Moreover, long-term use of bone conduction hearing AIDS can make the skin hard and cause pain. Air conduction hearing AIDS cover a wider range of sound frequencies, and the sounds heard are more natural and clearer. The hair cells in our inner ear have different sensitivities to sounds of different frequencies. The lower the frequency of the sound wave, the closer the location of the maximum amplitude is to the cochlear apex. The higher the sound frequency, the closer the location of the maximum amplitude is to the base of the cochlea. When sounds of different frequencies reach the hair cells - auditory nerve fiber impulses - auditory centers in different parts of the body, they will produce sounds of different tones.
Under normal circumstances, when chatting with friends, we rely heavily on the different emotional feelings brought by the tone of voice. Only by being able to hear the tone can one truly understand what others are saying. However, bone conduction hearing AIDS have certain limitations in output. Compared with air conduction hearing AIDS, they have lower output power, a narrower frequency range, more distortion, and also affect the directionality of sound.
Supplementary: Bone conduction hearing AIDS are not bad, but they are suitable for specific groups of people: those with external ear deformities, chronic otitis media, ear canal atresia, and other conditions that prevent the use of traditional air conduction devices. When purchasing a hearing aid, make sure to look for the National Class II Medical Device Registration Certificate, which is equivalent to the "ID card" of the hearing aid. At the same time, never believe the false promotion of "no fitting required". Don't be carried away by the claims of "low price" and "omnipotent". Do more research and learn more. If you spend money and make your already injured ears even worse off, it would be a loss not worth it.